A high frequency filter which contains a conventional transmission line type resonator is described referring to drawings. FIG. 24 is a perspective view of a high frequency filter which contains a conventional transmission line type resonator.
Referring to FIG. 24, conventional high frequency filter 1 includes terminal 3 for external connection, half-wavelength transmission line type resonator 4, half-wavelength transmission line type resonator 5, and terminal 6 for external connection, which are disposed in the order of above description on dielectric sheet 2. These terminal 3 for external connection, transmission line type resonator 4, transmission line type resonator 5, and terminal 6 for external connection are in the state of capacitive coupling to each other.
The element length of transmission line type resonators 4, 5 in the conventional high frequency filter 1 is determined depending on the dielectric constant of dielectric sheet 2.
As to the prior art technical documentation related to the present patent application, “MICROWAVE FILTERS, IMPEDANCE-MATCHING NETWORKS, AND COUPLING STRUCTURES” by G. L. Matthaei, L. Young and E. M. T. Jones, Artech House (Norwood, Mass.) 1980, offers known information.
In the above-described conventional high frequency filter 1, whose transmission line type resonators 4, 5 are of the right hand system, the electric resistance of transmission line type resonators 4, 5 converts the high frequency current in transmission line type resonators 4, 5 into thermal energy. This results in a substantial insertion loss in the transmission characteristic of high frequency filter 1.